Thread-nipper-releasing device for sewing-machines



e. s. GATCHELL. THREAD NIPPER RELEASING DEVICE FOR SEWING MACHINES.

APPLICATION FILED MAYZI. I918.

1,327,232. Patented Jan. 6, 1920.

3 SHEETS-SHEET I.

WITNESSES INVENTOR M ATTORNEY G. s. GATCHELL.

THREAD NIPPER RELEA'SING DEVICE FOR SEWlNG MACHINES.

APPLICATION FILED MAY 21. 1918.

1,327,232. Patented Jan. 6, 1920.

3 SHEETS-SHEET 2- A u A 3 R w m w WITNESSES lNVENTOR Maw. 74; W

G. S. GATCHELL.

THREAD NIPPER RELEASING DEVICE FOR SEWING MACHINES.

APPLICATION FILED MAY 2|. I9l8. 2 a

Patented J an. 6, 1920.

INVENTOR WITNESSES ATTORNEY nnrr s re- @i nnr,

GEORGE S. GATCHELL, 0F EOSELLE PARK, JERSEY, ASSIGNOR TO THE SINGER,

MANUFACTURING COMPANY, A CORPORATION OF NEW JERSEY. i 1

THREAD-NIPPER-RELEASING DEVICE FOR SEWING-MACHINES.

Patented Jan. 6, 1920.

Application filed May 21, 1918. Serial No. 235,772.

To all whom it may concern:

Be it known that I, Gnoncn S. GA'roHnLL, a citizen of the United States, residing at Roselle Park, in the county of Union and State of New Jersey, have invented certain new and useful Improvements in Thread- Nipper-Releasing Devices for Sewing-Machines, of which the following is a specification, reference being had therein to the accompanying drawings.

This invention relates to sewing machines in which one or more needles cooperate with a threadcarrying looper to form readily raveling stitches of the well known doublechain type. Sewing machines of this type commonly employ a looper-thread controller for taking up and paying out thread to the looper as it seizes and sheds the needle-loops. A thread-nipper is also commonly employed at the supply side of the looper-thread controller to nip the thread while it is being drawn back from the looper and to release the thread during the last part of the advancing stroke of the looper, so that the latter may draw enough looper-thread through the nipper for the next stitch.

In stitching with a machine of the present type it is customary for the operator, upon reaching the end of a seam, to stop the machine and turn it forwardly by hand until the needles are down or, in other words, until the looper has shed the needleloops, and to then turn the machine backwardly to raise the needles from the work; the looper-beak being thereby caused to cross the line of seam in front of the needles during which movement it fails to seize needle-loops. This operation therefore frees the needle-threads from the looper and permits the finished Work to be drawn from under the presser-foot and the stitching threads to be severed in positions such that the needle-threads lead downward from the elevated needles. through the apertured presser-foot and rearwardly, while the looper-thread leads upwardly from the eye of the looper, through the apertured throatplate and rearwardly. A new seam may therefore be started immediately without further preliminary manipulation of the stitching threads adjacent the sewing point.

However, inasmuch as the looper-thread nipper is closed during the major portion of the stitch-forming cycle and is open only during the last part of the advancing stroke of the looper, corresponding to the last part of the up-stroke of the needles, it is neces-' sary for the operator, after reversing the machine, to exercise undue care and attention in finally stopping'the machine within the narrow limits when the nipper is normally open and the needle out of the work, in order that the looper-thread may run freely from the supply as the work is withdrawn.

Further difiiculties are occasioned by the fact that when the looper-thread controlling mechanism of a machine of the class described is constructed and adjusted to operate to the best advantage, the slack looperthread is all absorbed during the retraction of the looper by the stitch being formed and set up, so that when the looper reaches the end of its retracting strokeand the needles are at the end of their down stroke, the looper-thread is nipped and is free from slack between the nipper and the looper. When the machine is reversed to withdraw the needles and needle-loops, the nipper remains closed and the hump on the looperthread controller-cam which normally acts to absorb looper-thread during the first part of the retracting stroke of the looper and give up thread during the last part of said stroke, reverses its action and absorbs thread as the looper is advanced in front of the needles. The result is, that since the nipper is closed at this period of the cycle, the looper-thread is apt to be broken as there is insufficient slack thread to permit the looper to move to the end of its stroke.

The present invention therefore has for an object to provide a machine of the class i described which does not require to be stopped within certain narrow limits to permit the looper-thread to run freely during the removal of the work but in which the looper-thread will be released by the nipper when the machine is turned backward and stopped at any point when the needles are out of the work.

A further object of the invention is to provide a machine having looper-thread controlling and nipping mechanism so constructed that the slack looper-thread is all used up at the end of the retracting stroke of the looper and which may be stopped at this point in the cycle and reversely turned to lift the needles from the work without straining or breaking the looper-thread.

spring:

A further object of the invention is to provide a nipper releasing mechanism which is actuated automatically when the machine is reversed and which is noiseless while the machine is stitching.

Further objects of the invention will appear from the following description and claims.

To these ends, the looper-thread nipper mechanism which, in' the present emb0diment, consists of superposed nipper-springs acted upon by a cam, is provided with means acting automatically when the machine is turned backward to open the nipper-springs at a period in the cycle when they are nor mally closed. Preferably, the shaft carrying the nipper-actuating cam is provided with an auxiliary cam having a smoothly curved peripheral surface. The auxiliary cam runs idly during the normal operation of the machine and is provided with a low point which acts when the machine is turned in the reverse direction to elevate a thrustpiece pivotally secured to the upper nipper- The thrustpiece rides idly upon the auxiliary cam when the machine is stitching and, since the said auxiliary cam is free from abrupt angles or steps the device is free from clicking or other disagreeable noises.

In the accompanying drawings Figure l is a side elevation of a machine embodying the invention in its preferred form. Fig. 2 is a horizontal section through the stand ard of the machine above the level of the work-arm showing the latter in plan. Fig. 3 is a cross-section through the looperthread controller shaft showing the looperthread take-up cam and cooperating threadguides in side elevation. Fig. is a similar view of the looper-thread pull-off device. Fig. 5 is a similar view showing the threadnipper mechanism at the period in the cycle when the needles are substantially at their lowest point. Fig. 6 is a view similar to Fig. 5 showing the thrust-piece riding idly on the auxiliary cam; the nipper-springs being open due to the position of the main nipper-actuating cam. Fig. 7 is a view similar to Fig. 5 illustrating the lifting of the upper nippeuspring by the auxiliary cam when the machine is turned backward. Figs. 8 and 9 are detail elevation and plan views, respectively, of an auxiliary needlethread tension device carried by the needlebar. Fig. 10; is a perspective view of the nipper-springs and their supporting block. Fig. 11 is a diagram illustrating the relative timing of the needle, looper-thread take-up, looper-thread pull-off and looper-thread nipper.

As illustrated, the invention is embodied in a machine of which the various constructivenfeatures not herein specifically described are disclosed in my copending application Serial No. 185A4c6, filed August 10, 1917. The machine frame is formed with a base 1 from which rises the standard 2 carrying the hollow work-arm 3 and the overhanging bracket-arm l terminating in the hollow head 5 in which is journaled for reciprocation the needle-bar 6 carrying one or more needles 7 The needle or needles 7 cooperate in the usual manner with the thread-carrying looper 8 mounted on the looper-supporting shaft 9 extending within and longitudinally with the work-arm 3. Rocking movements are imparted to the looper-shaft to give to the looper its loop-seizing and -shedding components of motion transversely of the line of feed by means of the crank and pitinan connection 10 with the eccentric 11 on the main shaft 12. Endwise movements are imparted to the looper-shaft 9 to give to the looper sidewise or so called needleavoiding components of motion by means of an eccentric on the main-shaft embraced by one end of a pitman 13 the opposite end of which is connected to the upper arm lei of a lever fulcrumed on the cross-pin 15. The lower arm 16 of said lever is connected by a link 17 to the ball 18 at the rear end of the looper-shaft 9. As is customary, the looper is timed to begin its loop-seizing stroke as the needle-bar begins its ascent and its loop-shedding stroke as the needle bar begins its descent. The machine is equipped with suitable feeding mechanism which may be of the well known type including main and auxiliary feed-dogs 19 and 20 operating to full-in and feed the work lengthwise of the arm 3 in the manner described in my said copending application. A presser-foot 21 holdsthe work in contact with the feed-dogs during the feeding stroke.

Extending within and transversely of the rear end or the workarm 3 is a looperthread controller shaft 22 to which is fixed a gear 23 meshing with the gear 24 which. in turn, meshes with the gear 25 fixed to the main-shaft 12. As the gears 28 and 25 are of the same size, the shaft 22 will be rotated at the same speed as the main-shaft and will therefore make one complete rotation for each stitclrforming cycle. The shaft 22 carries a looper-thread pull-off cam 26 comprising spaced. disks of similar shape between which is mounted a stripper 27' acting in the usual manner to prevent the thread being carried around by the cam. The usual fork 28 having thread-eyes 29 is provided for guiding the thread across the active peripheral portion of the cam.

Fixed to the opposite end of the shaft 22 is the looper-thread take-up cam cooperating with which are the stripper 31 and threadguiding fork 32, formed with threadeyes 33, these parts being similar in construction to the thread guiding accessories for the pull-off cam 26. The shank of the fork 32 is pivotally secured to the cars 34 which project upwardly from the block 35 fixed to the lug 36 cast within the work arm 3.

Mounted upon the shaft 22, intermediate the pull-off and take-up cams 26 and 30, respectively, is the main nipper-actuating cam 37 having a higher concentric portion 0 beginning at the point 38 and ending at the point 39 and a lower concentric portion 0 extending from the point 40 to the point 41. Secured within a suitable seat in a lateral arm 42 of the block 35 are the upper and lower nipper-springs 43 and 44, respectively, the free ends of which normally spring apart and extend over the nipper closing cam 37; the lower spring 44 bearing yieldingly upon said cam. As the cam rotates, the rise between the points 41 and 38 lifts the spring 44 causing it to pinch or lock the looper-thread against the upper spring 43, as will be readily understood. After the point 39 has passed the nipping element 44 the latter will spring away from the upper nipping element 43 and release the thread.

Fixed to one side face of the nipper-cam 37 is the smaller auxiliary nipper-cam 45 the lowest point of which is at 46 and which is provided with higher concentric portions 47 and 48. A block 49 is screwed to the upper nipper-spring 43 and is formed with an ear 50, to which is pivotally secured at 51, the upper end of a thrust-piece 51 the lower extremity of which bears upon the smoothly curved peripheral surface of the cam 45. The free end of a relatively weak leaf spring 52 mounted upon the block 49 presses upwardly under a lateral car 53 on the thrustpiece 51 and tends to turn the latter into engagement with the st0p-shoulder 54 formed on the block 49. The length of the thrust-piece 51 is such that when the nippersprings are closed, Fig. 5, it reaches to the low point 46 of the cam 45 and the center of the lower end face of the thrust-piece lies substantially in coincidence with a line connecting the center of the shaft 22 with the center of the pivot-screw 51. At this point of the cycle the thrust-piece is close to but is not in contact with the stop-shoulder 54.

The needle-bar carries a bracket 55 including a transverse arm 56 channeled in its forward face to receive a pair of tension plates 57 loosely mounted upon screw-pins 58 and pressed yieldingly toward the bottom face 59 of the channeled arm 56 by springs 60. Threadguiding slots 61 cut in the upper and lower side walls of the channeled arm 56 guide for four needle-threads beneath the plates 57, two threads being acted upon by each plate. The springs 60 are quite weak and the plates 57 therefore put a very light tension upon the needle-threads,

sufficient to pull upon the threads during the first part of the up-stroke of the needles and prevent the formation of needle-loops in front of the needles.

During the normal operation of the machine the looper advances in rear of the needles (at the left of the needles, Fig. 1) to seize the needle-loops and retracts in front of the needles to shed the needle-loops. The operator, upon stopping the machine at the end of a seam, turns the machine forwardly by hand until the needles are sub stantially at the end of their down-stroke to insure that the looper has shed the needleloops. Referring to Fig. 11 it will be seen that at this point of the cycle the nippers are closed, the pull-off has drawn about three-fourths of the amount of thread required for a stitch and one of the lower points of the looper-thread take-up 30 is in engagement with the looper-thread. Also, at this'point, the looper is fully retracted and the nipper-actuating cams occupy the position shown in Fig. 5. As the operator now turns the machine in the reverse direc tion to elevate the. needles, the thrust-piece 51 is shifted into engagement with the stop 54 and is thereafter lifted to the position shown in Fig. 7 by the cam-rise leading from the point 46 to the concentric portion 47 of the cam 45. The looper-thread is therefore released at the beginning of the reverse movement of the machine, that is, during the first part of the up-stroke of the needles, and when the looper is about to advance in front of the needles.

As the machine is turned farther in the reverse direction, the pull-0E cam, in back ing up, gives up thread through the open nipper to the looper, thus permitting the latter to move to the forward end of its stroke without straining the looper-thread or pulling it through the usual looper-thread tension device, not shown. During the advance of the looper in front of the needles, the tension plates 57 hold the needle-threads fixed relatively to the rising needle-bar and hence prevent the throwing out of the needleloops in front of the needles. The possibility of the looper seizing needle-loops during the reverse movement of the machine is therefore entirely eliminated.

As the point 38 of the main nipper actuating-cam 37 passes the spring 44 during the reverse movement, Fig. 7, the point 47 at the end of the concentric portion 47 of the auxiliary cam 45 passes the lower extremity of the thrust-piece 51 and thus the nipperwork but may stop it at any point when the needles are out of the work, thus avoiding the loss of time incident to careful stopping of the machine between narrow limits.

Prior to the removal of the work the operator depresses the rearward arm of the usual treadlecontrolled presser-foot lifting lever 62, thus efiecting the release of the various tension-devices 63 for the needle and looper threads in the manner described in my said copending application. As soon as the machine is started, the lower end of the thrust-piece 51 is carried forwardly, as shown in Fig. 6, and the nipper mechanism is at once restored to normal operative condition.

It will be noticed that the auxiliary cam is provided with a smoothly curved periph= cry and referring particularly to Figs. 5 and 6, when the machine is running forwardly the lower end of the thrust-piece rides idly upon the smooth periphery of the auxiliary cam. Once during each rotation of the aux iliary cam the thrust-piece moves into the position shown in Fig. 5 with its lower end in contact with the low point 46 of the cam. At this point, however, the beginning of the eccentric portion 48 immediately comes into action to prevent the thrust-piece from snapping past the low point 46 under the influence of the spring 52 and contacting with the stop shoulder 54: with an objectionable clicking noise.

The invention is not to be understood as limited to the exact form and arrangement of the parts described as various modifications within the scope of the invention will be apparent from the foregoing disclosure to those skilled in the art.

Having thus set forth. the nature of the invention, what I claim herein is 1. In a sewing machine, in combination, stitclrformingmechanism including an eyepointed needle and a thread-carrying looper coeperating therewith to form stitches, an intermittently acting thread-nipper for arresting the movement of the looper-thread from the supply during a certain period of each stitch-forming cycle, and normally in effective means acting automatically upon the reversal of the machine to open said nipper and release the looper-thread.

2. In a sewing machine, in combination, a reciprocating needle, a thread-carrying looper, a' looper-thread nipper, actuating mechanism for intermittently closing said nipper upon the looper-thread during each cycle in the normal operation of the ma chine, and means independent of said actuating mechanism for opening said nipper to release the looper-thread when the machine is turned backward.

3. In a sewing machine, in combination,

stitch-forming mechanism including an eyepointed needle and a thread-carrying looper cooperating therewith to form stitches, an

intern'iittently acting thread-nipper for ar resting the movement of the looper-thread tron'i the supply during a certain period of each stitch-forming cycle, and a cam-operated device ineffective during the normal operation of the machine and acting automatically upon reversal of the machine to open said nipper and release the looperthread.

4:. In a sewing machine, in combination, stitch-forming mechanism including an eyepointed needle and a thread-carrying looper cooperating therewith to form stitches, an intermittently acting thread-nipper for arresting the movement of the looper-thread from the supply during a certain period of each stitch-forming cycle including a por ticn. oi the cycle when the needle is out of the work, and normally ineffective means i acting when the machine is turned backward to open said nipper and hold it open over that portion of the cycle when the needle is out of the work and the nipper is normally closed.

A thread-nipper mechanism for sewing machines comprising coacting thread-nipping elements for holding the thread against movement, a primary cam for controlling the times of opening and closing of the said nipper elements, an auxiliary cam, and a thrust-piece connected to one of said nipping elements, said auxiliary cam being formed with a low point permitting movement of said thrust-piece to operative position and being further formed with an eccentric portion for shifting said thrust-piece to separate said nipper elements when the machine is turned backward.

6. A threa(ll-restraining device for sewing machines comprising a thread-engaging element, a cam having a smoothly curved ac tive surface, a thrust-piece connected to said thread-engaging element and riding idly and noiselessly upon said cam during the normal operation of the machine, said cam being formed with a low point connected to the remainder of the cam by a smoothly curved surface permitting noiseless move ment of said thrust-piece to operative position once during each rotation of said cam and being further formed with an eccentric portion connected to said low point for shifting said thrust-piece to release the thread when the machine is turned backward.

7. In a sewing machine, in combination, stitch-forming mechanism including an eyepointed reciprocating needle and a complemental thread-carrying looper, a looperthread take-up, a looper-thread pull-off, an intermittently acting thread-nipper operating on the looper-thread between said takeup and pull-01f, said pull-off being so timed that it has absorbed some slack thread from the supply when the needles are down and the looper retracted, and a device ineffective during the normal operation of the machine and acting when the machine is turned backward to open said thread-nipper as the needle rises, thereby permitting the thread given up by the pull-off in its reversed movement to pass through the nipper to the advancing looper and prevent straining of the looper-thread as the looper moves to the end of its stroke.

8. Thread-nipper mechanism for sewing machines comprising, coacting thread-nipping elements, actuating mechanism for intermittently closing said thread-nipping elements upon the thread during the normal (operation of the machine, and means ineffective While the machine is stitching and acting automatically upon reversal of the machine to open the thread-nipping elements.

9. Thread-nipper mechanism for sewing machines comprising, coacting thread-nipping elements, a main cam acting upon one of said elements to cause it to lock the thread intermittently against the other of said elements, an auxiliary cam, and a thrust-piece carried by said second mentioned element and acted upon by said auxiliary cam when themachine is turned backward to effect the separation of said elements and the consequent release of the looper-thread.

10. Thread-nipper mechanism for sewing machines comprising a pair of coacting thread-nipping elements, a nipper-actuating shaft, a main nipper-actuating cam mounted upon said shaft and acting to close the nipper elements intermittently during the normal operation of the machine, an auxiliary nipper-operating cam mounted upon said shaft and a thrust-piece connected to one of said nipper elements, said auxiliary cam having a low point permitting the thrustpiece to assume operative position and open the nippers when the machine is turned backward.

11. In a sewing machine, in combination, stitch-forming mechanism including a reciprocating eye-pointed needle and a threadcarrying looper cooperating therewith to form two-thread chain-stitches, a main-shaft for operating said needle and looper, a thread-nipper for the looper thread, a thread-nipper actuating shaft distinct from said main-shaft, primary operative connections between said nipper and nipper-actuating shaft for intermittently closing said nipper upon the looper-thread during the normal operation of the machine, and auxiliary operative connections between said nipper and nipper-shaft ineffective during the normal operation of the machine but acting when the machine is turned backward to open the nipper and release the looper threadv 12. A thread nipper releasing device for sewing machines comprising a shaft, a cam carried by said shaft and having a low point, intermittent thread nipper mechanism comprising coacting nipper elements, a pivotally mounted thrust-piece connected to one of said elements and riding idly upon said cam during the normal operation of the machine, and a stop for arresting pivotal movement of said thrust-piece when said shaft is turned backwardly, the pivot of said thrust-piece being so related to the axis of said shaft that at one point in the revolution of said cam as its low point reaches the thrust-piece the point of contact of the latter with the cam shifts into substantial coincidence with a line joining the centers of said pivot and shaft, whereby upon reversal of the machine the thrustpiece is carried into engagement with said stop and elevated to open the nippers.

13. A thread-nipper releasing device for sewing machines comprising, a shaft, a cam carried by said shaft and having a smoothly curved active surface including a low point, coacting nipper elements, a pivotally mounted thrust piece connected to one of said elements and riding idly and noiselessly upon said cam during the normal operation of the machine, and a stop mounted inde pendently of said shaft for arresting the pivotal movement of said thrust-piece when the machine is turned backward.

14:. A thread-nipper releasing device for sewing machines comprising, a shaft, a cam carried by said shaft and having a low point, coacting nipper elements, a pivotally mounted thrust-piece connected to one of said elements and riding idly upon said cam during the normal operation of the machine, and a stop carried by one of said nipper elements for arresting the pivotal movement of said thrust-piece when the machine is turned backward.

15. In a sewing machine, in combination, a reciprocating needle, a thread-carrying looper, means for advancing and retracting said looper to seize and shed needle-loops, an intermittent looper-thread nipper acting to lock the thread against movement during a part of each sticl1forming cycle, a looperthread controller cooperating with said looper, the parts being so constructed and timed that the looper-thread is held nipped and is free from slack when the looper is at the end of its retracting stroke, and a nipper releasing device acting, when the machine is turned. backward from this point preparatory to removal of the work, to free the looper-thread and prevent the straining thereof by the looper.

In testimony whereof, I have signed my name to this specification.

GEORGE S. GATCHELL. 

